#!/usr/bin/env python3

# A Python script to generate a single PDF document with all the tldr pages. It works by generating
# intermediate HTML files from existing md files using Python-markdown, applying desired formatting
# through CSS, and finally rendering them as PDF. There is no LaTeX dependency for generating the PDF.

import os
import sys
import glob
import re
import markdown
import argparse

from weasyprint import HTML

def main(loc, colorscheme):

  oslist = []
  allmd = []
  group = []
  ap = []

  # Checking correctness of path
  if not os.path.isdir(loc):
    print("Invalid directory. Please try again!", file = sys.stderr)
    sys.exit(1)

  # Writing names of all directories inside 'pages' to a list
  for os_dir in os.listdir(loc):
    oslist.append(os_dir)

  oslist.sort()

  # Required strings to create intermediate HTML files
  header = '<!doctype html><html><head><meta charset="utf-8"><link rel="stylesheet" href="basic.css">'
  if colorscheme != "basic":
    header += '<link rel="stylesheet" href="' + colorscheme + '.css"></head><body>\n'
  header += "</head><body>\n"
  footer = "</body></html>"
  title_content = "<h1 class=title-main>tldr pages</h1><h4 class=title-sub>Simplified and community-driven man pages</h4></body></html>"

  # Creating title page
  with open("title.html", "w") as f:
    f.write(header + title_content)

  group.append(HTML("title.html").render())

  for operating_sys in oslist:

    i = 1

    # Required string to create directory title pages
    dir_title = "<h2 class=title-dir>" + operating_sys.capitalize() + "</h2></body></html>"

    # Creating directory title page for current directory
    with open("dir_title.html", "w") as os_html:
      os_html.write(header + dir_title)

    group.append(HTML("dir_title.html").render())

    # Creating a list of all md files in the current directory
    for temp in glob.glob(os.path.join(loc, operating_sys, "*.md")):
      allmd.append(temp)

    # Sorting all filenames in the directory, to maintain the order of the PDF
    allmd.sort()

    # Conversion of Markdown to HTML
    for md in allmd:

      with open(md, "r") as inp:
        text = inp.readlines()

      with open("htmlout.html", "w") as out:
        out.write(header)

        for line in text:
          if re.match(r'^>', line):
            line = line[:0] + '####' + line[1:]
          html = markdown.markdown(line)
          out.write(html)
        out.write(footer)

      group.append(HTML("htmlout.html").render())
      print("Rendered page {} of the directory {}".format(str(i), operating_sys))
      i += 1

    allmd.clear()

  # Merging all the documents into a single PDF
  for doc in group:
    for p in doc.pages:
      ap.append(p)

  # Writing the PDF to disk, preserving metadata of first tldr page
  group[2].copy(ap).write_pdf('tldr.pdf')

  if os.path.exists("tldr.pdf"):
    print("\nCreated tldr.pdf in the current directory!\n")

  # Removing unnecessary intermediate files
  try:
    os.remove("htmlout.html")
    os.remove("title.html")
    os.remove("dir_title.html")
  except OSError:
    print("Error removing temporary file(s)")


if __name__ == "__main__":

  # Unless specified otherwise by the user, this is the default colorscheme
  colorscheme = "basic"

  # Parsing the arguments
  parser = argparse.ArgumentParser()
  parser.add_argument("dir_path", help = "Path to tldr 'pages' directory")
  parser.add_argument("-c", choices=["solarized-light", "solarized-dark"], help="Color scheme of the PDF")
  args = parser.parse_args()

  loc = args.dir_path
  if args.c == "solarized-light" or args.c == "solarized-dark":
    colorscheme = args.c

  main(loc, colorscheme)
